....so you posted multiple threads to spam our forums with your request?
....that doesnt exactly encourage us to help you out.
as you described the problem could be quite a number of things and it is impossible to tell without you either describing what you did, specifics of how you got it working, or by you doing a series of tests. in general if you dont know what a button does, dont screw with it. if you want to know what it does there is a book called a manual which you should have read.
-does the tv actually turn on but remain black (no signal) or does the tv not turn on. if it turns on you may have changed the input to one with no signal. after a few seconds of no signal some tvs may have a powersave feature which dims/turns the tv off again.
-if it is not the input and you are convinced you changed a setting perhaps look in the manual under "factory reset" and follow the steps.
-if both do not work then try playing with the buttons writing down what you do and list the command which turned the tv on finally.
there is no magic "Fix it" button. you need to try these things out. since you managed to turn it on.. i will assume there is nothing electrically or physically wrong with the television.